1. Field of the Invention
This invention relates to a sewing machine structure and, more particularly, to a sewing machine structure that prevents oil inside the sewing machine from leaking out onto a cloth that is being sewed.
2. Description of the Related Art
In general, as shown in FIG. 5, an arm 1 of a lock stitching type sewing machine (hereinafter referred to as "a sewing-machine arm") has an opening 2, which is closed with an arm cover 3. By removing the arm cover 3 to expose the inside of the sewing-machine arm, it is possible to repair the interior of the sewing machine with ease and high efficiency.
A number of high-speed components are located inside the sewing-machine arm 1. When those components operate, oil on those components is scattered about. If the sewing-machine arm 1 is not suitably closed with the arm cover 3, as shown in FIG. 6, oil O in the sewing-machine arm 1 may leak out through the gap between the sewing-machine arm 1 and the arm cover 3 and stain a piece of cloth being sewed. To solve this problem, a packing material 4 is typically set between the sewing-machine arm 1 and the arm cover 3 to sufficiently seal the opening of the arm 1 and prevent the oil in the sewing-machine arm 1 from leaking out as shown in FIGS. 5 and 7.
However, as described above, the arm cover 3 is detachably engaged with the sewing-machine arm 1. Hence, as the arm cover 3 is repeatedly engaged with and disengaged from the sewing-machine arm 1, the packing material 4 gradually deteriorates, and eventually requires replacement. Moreover, the configuration of the packing material 4 depends on the sewing machine; that is, different sewing machines have different packing materials 4, which makes the maintenance of sewing machines rather troublesome.